1. Field of the Invention
The present invention relates to a semiconductor wafer wet processing device used in wet processes such as the cleaning of a semiconductor wafer during the fabrication of a semiconductor device.
2. Discussion of Related Art
The fabricating process of a semiconductor device includes various kinds of wafer wet processes. Particularly, a semiconductor wafer cleaning technique is of importance in a semiconductor device fabricating process. Accordingly, there has been developed an apparatus for a wafer wet process including wafer cleaning. Also, there is the overflow method of U.S. Pat. No. 5,293,373 applied to a conventional semiconductor wafer wet processing device which performs the wet process cleaning of a semiconductor wafer while a semiconductor wafer is inserted in a processing tank body. In the overflow method, the process solution, such as cleaning water, overflows onto the floor.
FIG. 1 is a cross-sectional view of a conventional wafer wet process device utilizing the overflow method.
The conventional wafer wet process device utilizing the overflow method comprises a container A provided with a supply line 12 containing a supply hole 11-2, a processing tank body 11 which contains a process solution which overflows over a wall 11-1, and a wafer carrying bucket 13 such as a boat or a cassette disposed in the processing tank body 11. The supply hole is formed at the bottom of the processing tank body. A plurality of wafers 10 are erectly arranged in the wafer carrying bucket 13, and a wafer contact 13-1 such as an inserting groove is formed on the lower side of the wafer carrying bucket 13 for mounting the wafer, as shown in the enlarged view of FIG. 1 (a). Since the wafer carrying bucket 13 has holes through its bottom and top, a cleaning water or a chemical solution such as a process solution introduced into the processing tank body 11 cleans the wafers and can perform chemical reactions such as etching, by passing a chemical solution between the wafers.
The process solution overflowing the wall of the processing tank body 11-1 through conduit 15 is recycled after the process solution is filtered by a filter 16. A pump 17 is used for supplying the processing solution, for instance, for circulating the process solution. A problem is caused when a conventional apparatus employs the overflow method in which the process solution flows up and down. Thus, the contaminant materials always remain on the wafer contact 13-1 formed on the lower side of the wafer carrying bucket 13, that is, the inserting groove for fixing the wafers. These contaminant materials move up and down according to the flow of the process solution, and as a result, there is the problem that the contaminant materials come into frequent contact with the surface of wafer 10.
For solving these problems, a conventional semiconductor wafer wet processing device utilizes a down-flowing method in which a process solution flows downward (see 24th Symposium On ULSI ULTRA Clean Technology, Japan)
FIG. 2 is a cross-sectional view of a conventional semiconductor wafer wet processing device which utilizes the down-flowing method. As shown in FIG. 2, a conventional semiconductor wafer wet processing device which utilizes a down-flow method comprises a container A which houses a processing tank body wall 21-1, a conduit 25 which surrounds the wall 21-1, and an exhaust hole 21-3 formed at the bottom of the body 21 through which the solution is exhausted. The process solution enters the processing tank body from the conduit 25 and flows up and down. This conventional device using a down-flow method has considerably improved the contaminant problem since the wafer contact 23-1 of the wafer carrying bucket 23 is positioned at or near the hole 21-3 of the processing tank body and thus the contaminant materials come into less contact with the wafer 20.
However, in the above-described conventional devices of the overflow and down-flow methods as shown in FIGS. 1 and 2, respectively, there is the disadvantage that they are insufficient in achieving an effective processing effect for the side and corner of the wafer. Because the process solution flows only in a uniform direction in these two methods, the cleaning and wet processing effect is reduced for that portion of the side or corner of the wafer which is not directly under the influence of the flow.